diff --git a/flang/include/flang/Runtime/io-api.h b/flang/include/flang/Runtime/io-api.h
index 1b6c4f5d6a65c..328afc715a3f1 100644
--- a/flang/include/flang/Runtime/io-api.h
+++ b/flang/include/flang/Runtime/io-api.h
@@ -92,18 +92,18 @@ constexpr std::size_t RecommendedInternalIoScratchAreaBytes(
 
 // Internal I/O to/from character arrays &/or non-default-kind character
 // requires a descriptor, which is copied.
-Cookie IONAME(BeginInternalArrayListOutput)(const Descriptor &,
+Cookie IODECL(BeginInternalArrayListOutput)(const Descriptor &,
     void **scratchArea = nullptr, std::size_t scratchBytes = 0,
     const char *sourceFile = nullptr, int sourceLine = 0);
-Cookie IONAME(BeginInternalArrayListInput)(const Descriptor &,
+Cookie IODECL(BeginInternalArrayListInput)(const Descriptor &,
     void **scratchArea = nullptr, std::size_t scratchBytes = 0,
     const char *sourceFile = nullptr, int sourceLine = 0);
-Cookie IONAME(BeginInternalArrayFormattedOutput)(const Descriptor &,
+Cookie IODECL(BeginInternalArrayFormattedOutput)(const Descriptor &,
     const char *format, std::size_t formatLength,
     const Descriptor *formatDescriptor = nullptr, void **scratchArea = nullptr,
     std::size_t scratchBytes = 0, const char *sourceFile = nullptr,
     int sourceLine = 0);
-Cookie IONAME(BeginInternalArrayFormattedInput)(const Descriptor &,
+Cookie IODECL(BeginInternalArrayFormattedInput)(const Descriptor &,
     const char *format, std::size_t formatLength,
     const Descriptor *formatDescriptor = nullptr, void **scratchArea = nullptr,
     std::size_t scratchBytes = 0, const char *sourceFile = nullptr,
@@ -111,20 +111,20 @@ Cookie IONAME(BeginInternalArrayFormattedInput)(const Descriptor &,
 
 // Internal I/O to/from a default-kind character scalar can avoid a
 // descriptor.
-Cookie IONAME(BeginInternalListOutput)(char *internal,
+Cookie IODECL(BeginInternalListOutput)(char *internal,
     std::size_t internalLength, void **scratchArea = nullptr,
     std::size_t scratchBytes = 0, const char *sourceFile = nullptr,
     int sourceLine = 0);
-Cookie IONAME(BeginInternalListInput)(const char *internal,
+Cookie IODECL(BeginInternalListInput)(const char *internal,
     std::size_t internalLength, void **scratchArea = nullptr,
     std::size_t scratchBytes = 0, const char *sourceFile = nullptr,
     int sourceLine = 0);
-Cookie IONAME(BeginInternalFormattedOutput)(char *internal,
+Cookie IODECL(BeginInternalFormattedOutput)(char *internal,
     std::size_t internalLength, const char *format, std::size_t formatLength,
     const Descriptor *formatDescriptor = nullptr, void **scratchArea = nullptr,
     std::size_t scratchBytes = 0, const char *sourceFile = nullptr,
     int sourceLine = 0);
-Cookie IONAME(BeginInternalFormattedInput)(const char *internal,
+Cookie IODECL(BeginInternalFormattedInput)(const char *internal,
     std::size_t internalLength, const char *format, std::size_t formatLength,
     const Descriptor *formatDescriptor = nullptr, void **scratchArea = nullptr,
     std::size_t scratchBytes = 0, const char *sourceFile = nullptr,
@@ -139,63 +139,63 @@ Cookie IONAME(BeginInternalFormattedInput)(const char *internal,
 // If handleError is false, and the unit number is out of range, the program
 // will be terminated. Otherwise, if unit is out of range, a nonzero Iostat
 // code is returned and ioMsg is set if it is not a nullptr.
-enum Iostat IONAME(CheckUnitNumberInRange64)(std::int64_t unit,
+enum Iostat IODECL(CheckUnitNumberInRange64)(std::int64_t unit,
     bool handleError, char *ioMsg = nullptr, std::size_t ioMsgLength = 0,
     const char *sourceFile = nullptr, int sourceLine = 0);
-enum Iostat IONAME(CheckUnitNumberInRange128)(common::int128_t unit,
+enum Iostat IODECL(CheckUnitNumberInRange128)(common::int128_t unit,
     bool handleError, char *ioMsg = nullptr, std::size_t ioMsgLength = 0,
     const char *sourceFile = nullptr, int sourceLine = 0);
 
 // External synchronous I/O initiation
 Cookie IODECL(BeginExternalListOutput)(ExternalUnit = DefaultOutputUnit,
     const char *sourceFile = nullptr, int sourceLine = 0);
-Cookie IONAME(BeginExternalListInput)(ExternalUnit = DefaultInputUnit,
+Cookie IODECL(BeginExternalListInput)(ExternalUnit = DefaultInputUnit,
     const char *sourceFile = nullptr, int sourceLine = 0);
-Cookie IONAME(BeginExternalFormattedOutput)(const char *format, std::size_t,
+Cookie IODECL(BeginExternalFormattedOutput)(const char *format, std::size_t,
     const Descriptor *formatDescriptor = nullptr,
     ExternalUnit = DefaultOutputUnit, const char *sourceFile = nullptr,
     int sourceLine = 0);
-Cookie IONAME(BeginExternalFormattedInput)(const char *format, std::size_t,
+Cookie IODECL(BeginExternalFormattedInput)(const char *format, std::size_t,
     const Descriptor *formatDescriptor = nullptr,
     ExternalUnit = DefaultInputUnit, const char *sourceFile = nullptr,
     int sourceLine = 0);
-Cookie IONAME(BeginUnformattedOutput)(ExternalUnit = DefaultOutputUnit,
+Cookie IODECL(BeginUnformattedOutput)(ExternalUnit = DefaultOutputUnit,
     const char *sourceFile = nullptr, int sourceLine = 0);
-Cookie IONAME(BeginUnformattedInput)(ExternalUnit = DefaultInputUnit,
+Cookie IODECL(BeginUnformattedInput)(ExternalUnit = DefaultInputUnit,
     const char *sourceFile = nullptr, int sourceLine = 0);
 
 // WAIT(ID=)
-Cookie IONAME(BeginWait)(ExternalUnit, AsynchronousId,
+Cookie IODECL(BeginWait)(ExternalUnit, AsynchronousId,
     const char *sourceFile = nullptr, int sourceLine = 0);
 // WAIT(no ID=)
-Cookie IONAME(BeginWaitAll)(
+Cookie IODECL(BeginWaitAll)(
     ExternalUnit, const char *sourceFile = nullptr, int sourceLine = 0);
 
 // Other I/O statements
-Cookie IONAME(BeginClose)(
+Cookie IODECL(BeginClose)(
     ExternalUnit, const char *sourceFile = nullptr, int sourceLine = 0);
-Cookie IONAME(BeginFlush)(
+Cookie IODECL(BeginFlush)(
     ExternalUnit, const char *sourceFile = nullptr, int sourceLine = 0);
-Cookie IONAME(BeginBackspace)(
+Cookie IODECL(BeginBackspace)(
     ExternalUnit, const char *sourceFile = nullptr, int sourceLine = 0);
-Cookie IONAME(BeginEndfile)(
+Cookie IODECL(BeginEndfile)(
     ExternalUnit, const char *sourceFile = nullptr, int sourceLine = 0);
-Cookie IONAME(BeginRewind)(
+Cookie IODECL(BeginRewind)(
     ExternalUnit, const char *sourceFile = nullptr, int sourceLine = 0);
 
 // OPEN(UNIT=) and OPEN(NEWUNIT=) have distinct interfaces.
-Cookie IONAME(BeginOpenUnit)(
+Cookie IODECL(BeginOpenUnit)(
     ExternalUnit, const char *sourceFile = nullptr, int sourceLine = 0);
-Cookie IONAME(BeginOpenNewUnit)(
+Cookie IODECL(BeginOpenNewUnit)(
     const char *sourceFile = nullptr, int sourceLine = 0);
 
 // The variant forms of INQUIRE() statements have distinct interfaces.
 // BeginInquireIoLength() is basically a no-op output statement.
-Cookie IONAME(BeginInquireUnit)(
+Cookie IODECL(BeginInquireUnit)(
     ExternalUnit, const char *sourceFile = nullptr, int sourceLine = 0);
-Cookie IONAME(BeginInquireFile)(const char *, std::size_t,
+Cookie IODECL(BeginInquireFile)(const char *, std::size_t,
     const char *sourceFile = nullptr, int sourceLine = 0);
-Cookie IONAME(BeginInquireIoLength)(
+Cookie IODECL(BeginInquireIoLength)(
     const char *sourceFile = nullptr, int sourceLine = 0);
 
 // If an I/O statement has any IOSTAT=, ERR=, END=, or EOR= specifiers,
@@ -214,33 +214,33 @@ Cookie IONAME(BeginInquireIoLength)(
 //     }
 //   }
 //   if (EndIoStatement(cookie) == FORTRAN_RUTIME_IOSTAT_END) goto label666;
-void IONAME(EnableHandlers)(Cookie, bool hasIoStat = false, bool hasErr = false,
+void IODECL(EnableHandlers)(Cookie, bool hasIoStat = false, bool hasErr = false,
     bool hasEnd = false, bool hasEor = false, bool hasIoMsg = false);
 
 // ASYNCHRONOUS='YES' or 'NO' on READ/WRITE/OPEN
 // Use GetAsynchronousId() to handle ID=.
-bool IONAME(SetAsynchronous)(Cookie, const char *, std::size_t);
+bool IODECL(SetAsynchronous)(Cookie, const char *, std::size_t);
 
 // Control list options.  These return false on a error that the
 // Begin...() call has specified will be handled by the caller.
 // The interfaces that pass a default-kind CHARACTER argument
 // are limited to passing specific case-insensitive keyword values.
 // ADVANCE=YES, NO
-bool IONAME(SetAdvance)(Cookie, const char *, std::size_t);
+bool IODECL(SetAdvance)(Cookie, const char *, std::size_t);
 // BLANK=NULL, ZERO
-bool IONAME(SetBlank)(Cookie, const char *, std::size_t);
+bool IODECL(SetBlank)(Cookie, const char *, std::size_t);
 // DECIMAL=COMMA, POINT
-bool IONAME(SetDecimal)(Cookie, const char *, std::size_t);
+bool IODECL(SetDecimal)(Cookie, const char *, std::size_t);
 // DELIM=APOSTROPHE, QUOTE, NONE
-bool IONAME(SetDelim)(Cookie, const char *, std::size_t);
+bool IODECL(SetDelim)(Cookie, const char *, std::size_t);
 // PAD=YES, NO
-bool IONAME(SetPad)(Cookie, const char *, std::size_t);
-bool IONAME(SetPos)(Cookie, std::int64_t);
-bool IONAME(SetRec)(Cookie, std::int64_t);
+bool IODECL(SetPad)(Cookie, const char *, std::size_t);
+bool IODECL(SetPos)(Cookie, std::int64_t);
+bool IODECL(SetRec)(Cookie, std::int64_t);
 // ROUND=UP, DOWN, ZERO, NEAREST, COMPATIBLE, PROCESSOR_DEFINED
-bool IONAME(SetRound)(Cookie, const char *, std::size_t);
+bool IODECL(SetRound)(Cookie, const char *, std::size_t);
 // SIGN=PLUS, SUPPRESS, PROCESSOR_DEFINED
-bool IONAME(SetSign)(Cookie, const char *, std::size_t);
+bool IODECL(SetSign)(Cookie, const char *, std::size_t);
 
 // Data item transfer for modes other than NAMELIST:
 // Any data object that can be passed as an actual argument without the
@@ -256,34 +256,34 @@ bool IONAME(SetSign)(Cookie, const char *, std::size_t);
 // Once the statement has encountered an error, all following items will be
 // ignored and also return false; but compiled code should check for errors
 // and avoid the following items when they might crash.
-bool IONAME(OutputDescriptor)(Cookie, const Descriptor &);
-bool IONAME(InputDescriptor)(Cookie, const Descriptor &);
+bool IODECL(OutputDescriptor)(Cookie, const Descriptor &);
+bool IODECL(InputDescriptor)(Cookie, const Descriptor &);
 // Formatted (including list directed) I/O data items
-bool IONAME(OutputInteger8)(Cookie, std::int8_t);
-bool IONAME(OutputInteger16)(Cookie, std::int16_t);
+bool IODECL(OutputInteger8)(Cookie, std::int8_t);
+bool IODECL(OutputInteger16)(Cookie, std::int16_t);
 bool IODECL(OutputInteger32)(Cookie, std::int32_t);
-bool IONAME(OutputInteger64)(Cookie, std::int64_t);
-bool IONAME(OutputInteger128)(Cookie, common::int128_t);
-bool IONAME(InputInteger)(Cookie, std::int64_t &, int kind = 8);
-bool IONAME(OutputReal32)(Cookie, float);
-bool IONAME(InputReal32)(Cookie, float &);
-bool IONAME(OutputReal64)(Cookie, double);
-bool IONAME(InputReal64)(Cookie, double &);
-bool IONAME(OutputComplex32)(Cookie, float, float);
-bool IONAME(InputComplex32)(Cookie, float[2]);
-bool IONAME(OutputComplex64)(Cookie, double, double);
-bool IONAME(InputComplex64)(Cookie, double[2]);
-bool IONAME(OutputCharacter)(Cookie, const char *, std::size_t, int kind = 1);
-bool IONAME(OutputAscii)(Cookie, const char *, std::size_t);
-bool IONAME(InputCharacter)(Cookie, char *, std::size_t, int kind = 1);
-bool IONAME(InputAscii)(Cookie, char *, std::size_t);
-bool IONAME(OutputLogical)(Cookie, bool);
-bool IONAME(InputLogical)(Cookie, bool &);
+bool IODECL(OutputInteger64)(Cookie, std::int64_t);
+bool IODECL(OutputInteger128)(Cookie, common::int128_t);
+bool IODECL(InputInteger)(Cookie, std::int64_t &, int kind = 8);
+bool IODECL(OutputReal32)(Cookie, float);
+bool IODECL(InputReal32)(Cookie, float &);
+bool IODECL(OutputReal64)(Cookie, double);
+bool IODECL(InputReal64)(Cookie, double &);
+bool IODECL(OutputComplex32)(Cookie, float, float);
+bool IODECL(InputComplex32)(Cookie, float[2]);
+bool IODECL(OutputComplex64)(Cookie, double, double);
+bool IODECL(InputComplex64)(Cookie, double[2]);
+bool IODECL(OutputCharacter)(Cookie, const char *, std::size_t, int kind = 1);
+bool IODECL(OutputAscii)(Cookie, const char *, std::size_t);
+bool IODECL(InputCharacter)(Cookie, char *, std::size_t, int kind = 1);
+bool IODECL(InputAscii)(Cookie, char *, std::size_t);
+bool IODECL(OutputLogical)(Cookie, bool);
+bool IODECL(InputLogical)(Cookie, bool &);
 
 // NAMELIST I/O must be the only data item in an (otherwise)
 // list-directed I/O statement.
-bool IONAME(OutputNamelist)(Cookie, const NamelistGroup &);
-bool IONAME(InputNamelist)(Cookie, const NamelistGroup &);
+bool IODECL(OutputNamelist)(Cookie, const NamelistGroup &);
+bool IODECL(InputNamelist)(Cookie, const NamelistGroup &);
 
 // When an I/O list item has a derived type with a specific defined
 // I/O subroutine of the appropriate generic kind for the active
@@ -294,9 +294,9 @@ bool IONAME(InputNamelist)(Cookie, const NamelistGroup &);
 // made such a generic interface inaccessible), these data item transfer
 // APIs enable the I/O runtime to make the right calls to defined I/O
 // subroutines.
-bool IONAME(OutputDerivedType)(
+bool IODECL(OutputDerivedType)(
     Cookie, const Descriptor &, const NonTbpDefinedIoTable *);
-bool IONAME(InputDerivedType)(
+bool IODECL(InputDerivedType)(
     Cookie, const Descriptor &, const NonTbpDefinedIoTable *);
 
 // Additional specifier interfaces for the connection-list of
@@ -304,56 +304,56 @@ bool IONAME(InputDerivedType)(
 // SetDelim(), GetIoMsg(), SetPad(), SetRound(), SetSign(),
 // & SetAsynchronous() are also acceptable for OPEN.
 // ACCESS=SEQUENTIAL, DIRECT, STREAM
-bool IONAME(SetAccess)(Cookie, const char *, std::size_t);
+bool IODECL(SetAccess)(Cookie, const char *, std::size_t);
 // ACTION=READ, WRITE, or READWRITE
-bool IONAME(SetAction)(Cookie, const char *, std::size_t);
+bool IODECL(SetAction)(Cookie, const char *, std::size_t);
 // CARRIAGECONTROL=LIST, FORTRAN, NONE
-bool IONAME(SetCarriagecontrol)(Cookie, const char *, std::size_t);
+bool IODECL(SetCarriagecontrol)(Cookie, const char *, std::size_t);
 // CONVERT=NATIVE, LITTLE_ENDIAN, BIG_ENDIAN, or SWAP
-bool IONAME(SetConvert)(Cookie, const char *, std::size_t);
+bool IODECL(SetConvert)(Cookie, const char *, std::size_t);
 // ENCODING=UTF-8, DEFAULT
-bool IONAME(SetEncoding)(Cookie, const char *, std::size_t);
+bool IODECL(SetEncoding)(Cookie, const char *, std::size_t);
 // FORM=FORMATTED, UNFORMATTED
-bool IONAME(SetForm)(Cookie, const char *, std::size_t);
+bool IODECL(SetForm)(Cookie, const char *, std::size_t);
 // POSITION=ASIS, REWIND, APPEND
-bool IONAME(SetPosition)(Cookie, const char *, std::size_t);
-bool IONAME(SetRecl)(Cookie, std::size_t); // RECL=
+bool IODECL(SetPosition)(Cookie, const char *, std::size_t);
+bool IODECL(SetRecl)(Cookie, std::size_t); // RECL=
 
 // STATUS can be set during an OPEN or CLOSE statement.
 // For OPEN: STATUS=OLD, NEW, SCRATCH, REPLACE, UNKNOWN
 // For CLOSE: STATUS=KEEP, DELETE
-bool IONAME(SetStatus)(Cookie, const char *, std::size_t);
+bool IODECL(SetStatus)(Cookie, const char *, std::size_t);
 
-bool IONAME(SetFile)(Cookie, const char *, std::size_t chars);
+bool IODECL(SetFile)(Cookie, const char *, std::size_t chars);
 
 // Acquires the runtime-created unit number for OPEN(NEWUNIT=)
-bool IONAME(GetNewUnit)(Cookie, int &, int kind = 4);
+bool IODECL(GetNewUnit)(Cookie, int &, int kind = 4);
 
 // READ(SIZE=), after all input items
-std::size_t IONAME(GetSize)(Cookie);
+std::size_t IODECL(GetSize)(Cookie);
 
 // INQUIRE(IOLENGTH=), after all output items
-std::size_t IONAME(GetIoLength)(Cookie);
+std::size_t IODECL(GetIoLength)(Cookie);
 
 // GetIoMsg() does not modify its argument unless an error or
 // end-of-record/file condition is present.
-void IONAME(GetIoMsg)(Cookie, char *, std::size_t); // IOMSG=
+void IODECL(GetIoMsg)(Cookie, char *, std::size_t); // IOMSG=
 
 // Defines ID= on READ/WRITE(ASYNCHRONOUS='YES')
-AsynchronousId IONAME(GetAsynchronousId)(Cookie);
+AsynchronousId IODECL(GetAsynchronousId)(Cookie);
 
 // INQUIRE() specifiers are mostly identified by their NUL-terminated
 // case-insensitive names.
 // ACCESS, ACTION, ASYNCHRONOUS, BLANK, CONVERT, DECIMAL, DELIM, DIRECT,
 // ENCODING, FORM, FORMATTED, NAME, PAD, POSITION, READ, READWRITE, ROUND,
 // SEQUENTIAL, SIGN, STREAM, UNFORMATTED, WRITE:
-bool IONAME(InquireCharacter)(Cookie, InquiryKeywordHash, char *, std::size_t);
+bool IODECL(InquireCharacter)(Cookie, InquiryKeywordHash, char *, std::size_t);
 // EXIST, NAMED, OPENED, and PENDING (without ID):
-bool IONAME(InquireLogical)(Cookie, InquiryKeywordHash, bool &);
+bool IODECL(InquireLogical)(Cookie, InquiryKeywordHash, bool &);
 // PENDING with ID
-bool IONAME(InquirePendingId)(Cookie, AsynchronousId, bool &);
+bool IODECL(InquirePendingId)(Cookie, AsynchronousId, bool &);
 // NEXTREC, NUMBER, POS, RECL, SIZE
-bool IONAME(InquireInteger64)(
+bool IODECL(InquireInteger64)(
     Cookie, InquiryKeywordHash, std::int64_t &, int kind = 8);
 
 // This function must be called to end an I/O statement, and its
diff --git a/flang/runtime/environment.cpp b/flang/runtime/environment.cpp
index b74067a377774..b2c9665a28df2 100644
--- a/flang/runtime/environment.cpp
+++ b/flang/runtime/environment.cpp
@@ -49,6 +49,7 @@ static void SetEnvironmentDefaults(const EnvironmentDefaultList *envDefaults) {
   }
 }
 
+RT_OFFLOAD_API_GROUP_BEGIN
 Fortran::common::optional<Convert> GetConvertFromString(
     const char *x, std::size_t n) {
   static const char *keywords[]{
@@ -68,6 +69,7 @@ Fortran::common::optional<Convert> GetConvertFromString(
     return Fortran::common::nullopt;
   }
 }
+RT_OFFLOAD_API_GROUP_END
 
 void ExecutionEnvironment::Configure(int ac, const char *av[],
     const char *env[], const EnvironmentDefaultList *envDefaults) {
diff --git a/flang/runtime/environment.h b/flang/runtime/environment.h
index 6c56993fb1d6e..b8b9f10e4e57f 100644
--- a/flang/runtime/environment.h
+++ b/flang/runtime/environment.h
@@ -31,7 +31,7 @@ RT_OFFLOAD_VAR_GROUP_END
 // External unformatted I/O data conversions
 enum class Convert { Unknown, Native, LittleEndian, BigEndian, Swap };
 
-Fortran::common::optional<Convert> GetConvertFromString(
+RT_API_ATTRS Fortran::common::optional<Convert> GetConvertFromString(
     const char *, std::size_t);
 
 struct ExecutionEnvironment {
diff --git a/flang/runtime/freestanding-tools.h b/flang/runtime/freestanding-tools.h
index 451bf13b9fa6d..9089dc6bcf53e 100644
--- a/flang/runtime/freestanding-tools.h
+++ b/flang/runtime/freestanding-tools.h
@@ -52,6 +52,11 @@
 #define STD_STRCPY_UNSUPPORTED 1
 #endif
 
+#if !defined(STD_STRCMP_UNSUPPORTED) && \
+    (defined(__CUDACC__) || defined(__CUDA__)) && defined(__CUDA_ARCH__)
+#define STD_STRCMP_UNSUPPORTED 1
+#endif
+
 namespace Fortran::runtime {
 
 #if STD_FILL_N_UNSUPPORTED
@@ -176,5 +181,19 @@ static inline RT_API_ATTRS char *strcpy(char *dest, const char *src) {
 using std::strcpy;
 #endif // !STD_STRCPY_UNSUPPORTED
 
+#if STD_STRCMP_UNSUPPORTED
+// Provides alternative implementation for std::strcmp(), if
+// it is not supported.
+static inline RT_API_ATTRS int strcmp(const char *lhs, const char *rhs) {
+  while (*lhs != '\0' && *lhs == *rhs) {
+    ++lhs;
+    ++rhs;
+  }
+  return static_cast<unsigned char>(*lhs) - static_cast<unsigned char>(*rhs);
+}
+#else // !STD_STRCMP_UNSUPPORTED
+using std::strcmp;
+#endif // !STD_STRCMP_UNSUPPORTED
+
 } // namespace Fortran::runtime
 #endif // FORTRAN_RUNTIME_FREESTANDING_TOOLS_H_
diff --git a/flang/runtime/io-api.cpp b/flang/runtime/io-api.cpp
index 3a86c9fa7375e..ccb5b576451dd 100644
--- a/flang/runtime/io-api.cpp
+++ b/flang/runtime/io-api.cpp
@@ -25,8 +25,9 @@
 #include <memory>
 
 namespace Fortran::runtime::io {
+RT_EXT_API_GROUP_BEGIN
 
-const char *InquiryKeywordHashDecode(
+RT_API_ATTRS const char *InquiryKeywordHashDecode(
     char *buffer, std::size_t n, InquiryKeywordHash hash) {
   if (n < 1) {
     return nullptr;
@@ -44,7 +45,7 @@ const char *InquiryKeywordHashDecode(
 }
 
 template <Direction DIR>
-Cookie BeginInternalArrayListIO(const Descriptor &descriptor,
+RT_API_ATTRS Cookie BeginInternalArrayListIO(const Descriptor &descriptor,
     void ** /*scratchArea*/, std::size_t /*scratchBytes*/,
     const char *sourceFile, int sourceLine) {
   Terminator oom{sourceFile, sourceLine};
@@ -54,14 +55,14 @@ Cookie BeginInternalArrayListIO(const Descriptor &descriptor,
               ->ioStatementState();
 }
 
-Cookie IONAME(BeginInternalArrayListOutput)(const Descriptor &descriptor,
+Cookie IODEF(BeginInternalArrayListOutput)(const Descriptor &descriptor,
     void **scratchArea, std::size_t scratchBytes, const char *sourceFile,
     int sourceLine) {
   return BeginInternalArrayListIO<Direction::Output>(
       descriptor, scratchArea, scratchBytes, sourceFile, sourceLine);
 }
 
-Cookie IONAME(BeginInternalArrayListInput)(const Descriptor &descriptor,
+Cookie IODEF(BeginInternalArrayListInput)(const Descriptor &descriptor,
     void **scratchArea, std::size_t scratchBytes, const char *sourceFile,
     int sourceLine) {
   return BeginInternalArrayListIO<Direction::Input>(
@@ -69,7 +70,7 @@ Cookie IONAME(BeginInternalArrayListInput)(const Descriptor &descriptor,
 }
 
 template <Direction DIR>
-Cookie BeginInternalArrayFormattedIO(const Descriptor &descriptor,
+RT_API_ATTRS Cookie BeginInternalArrayFormattedIO(const Descriptor &descriptor,
     const char *format, std::size_t formatLength,
     const Descriptor *formatDescriptor, void ** /*scratchArea*/,
     std::size_t /*scratchBytes*/, const char *sourceFile, int sourceLine) {
@@ -80,7 +81,7 @@ Cookie BeginInternalArrayFormattedIO(const Descriptor &descriptor,
               ->ioStatementState();
 }
 
-Cookie IONAME(BeginInternalArrayFormattedOutput)(const Descriptor &descriptor,
+Cookie IODEF(BeginInternalArrayFormattedOutput)(const Descriptor &descriptor,
     const char *format, std::size_t formatLength,
     const Descriptor *formatDescriptor, void **scratchArea,
     std::size_t scratchBytes, const char *sourceFile, int sourceLine) {
@@ -89,7 +90,7 @@ Cookie IONAME(BeginInternalArrayFormattedOutput)(const Descriptor &descriptor,
       sourceLine);
 }
 
-Cookie IONAME(BeginInternalArrayFormattedInput)(const Descriptor &descriptor,
+Cookie IODEF(BeginInternalArrayFormattedInput)(const Descriptor &descriptor,
     const char *format, std::size_t formatLength,
     const Descriptor *formatDescriptor, void **scratchArea,
     std::size_t scratchBytes, const char *sourceFile, int sourceLine) {
@@ -110,14 +111,14 @@ RT_API_ATTRS Cookie BeginInternalListIO(
               ->ioStatementState();
 }
 
-Cookie IONAME(BeginInternalListOutput)(char *internal,
+Cookie IODEF(BeginInternalListOutput)(char *internal,
     std::size_t internalLength, void **scratchArea, std::size_t scratchBytes,
     const char *sourceFile, int sourceLine) {
   return BeginInternalListIO<Direction::Output>(internal, internalLength,
       scratchArea, scratchBytes, sourceFile, sourceLine);
 }
 
-Cookie IONAME(BeginInternalListInput)(const char *internal,
+Cookie IODEF(BeginInternalListInput)(const char *internal,
     std::size_t internalLength, void **scratchArea, std::size_t scratchBytes,
     const char *sourceFile, int sourceLine) {
   return BeginInternalListIO<Direction::Input>(internal, internalLength,
@@ -125,7 +126,7 @@ Cookie IONAME(BeginInternalListInput)(const char *internal,
 }
 
 template <Direction DIR>
-Cookie BeginInternalFormattedIO(
+RT_API_ATTRS Cookie BeginInternalFormattedIO(
     std::conditional_t<DIR == Direction::Input, const char, char> *internal,
     std::size_t internalLength, const char *format, std::size_t formatLength,
     const Descriptor *formatDescriptor, void ** /*scratchArea*/,
@@ -138,7 +139,7 @@ Cookie BeginInternalFormattedIO(
               ->ioStatementState();
 }
 
-Cookie IONAME(BeginInternalFormattedOutput)(char *internal,
+Cookie IODEF(BeginInternalFormattedOutput)(char *internal,
     std::size_t internalLength, const char *format, std::size_t formatLength,
     const Descriptor *formatDescriptor, void **scratchArea,
     std::size_t scratchBytes, const char *sourceFile, int sourceLine) {
@@ -147,7 +148,7 @@ Cookie IONAME(BeginInternalFormattedOutput)(char *internal,
       sourceFile, sourceLine);
 }
 
-Cookie IONAME(BeginInternalFormattedInput)(const char *internal,
+Cookie IODEF(BeginInternalFormattedInput)(const char *internal,
     std::size_t internalLength, const char *format, std::size_t formatLength,
     const Descriptor *formatDescriptor, void **scratchArea,
     std::size_t scratchBytes, const char *sourceFile, int sourceLine) {
@@ -227,24 +228,22 @@ RT_API_ATTRS Cookie BeginExternalListIO(
   }
 }
 
-RT_EXT_API_GROUP_BEGIN
 Cookie IODEF(BeginExternalListOutput)(
     ExternalUnit unitNumber, const char *sourceFile, int sourceLine) {
   return BeginExternalListIO<Direction::Output, ExternalListIoStatementState>(
       unitNumber, sourceFile, sourceLine);
 }
-RT_EXT_API_GROUP_END
 
-Cookie IONAME(BeginExternalListInput)(
+Cookie IODEF(BeginExternalListInput)(
     ExternalUnit unitNumber, const char *sourceFile, int sourceLine) {
   return BeginExternalListIO<Direction::Input, ExternalListIoStatementState>(
       unitNumber, sourceFile, sourceLine);
 }
 
 template <Direction DIR>
-Cookie BeginExternalFormattedIO(const char *format, std::size_t formatLength,
-    const Descriptor *formatDescriptor, ExternalUnit unitNumber,
-    const char *sourceFile, int sourceLine) {
+RT_API_ATTRS Cookie BeginExternalFormattedIO(const char *format,
+    std::size_t formatLength, const Descriptor *formatDescriptor,
+    ExternalUnit unitNumber, const char *sourceFile, int sourceLine) {
   Terminator terminator{sourceFile, sourceLine};
   Cookie errorCookie{nullptr};
   ExternalFileUnit *unit{GetOrCreateUnit(
@@ -286,14 +285,14 @@ Cookie BeginExternalFormattedIO(const char *format, std::size_t formatLength,
   }
 }
 
-Cookie IONAME(BeginExternalFormattedOutput)(const char *format,
+Cookie IODEF(BeginExternalFormattedOutput)(const char *format,
     std::size_t formatLength, const Descriptor *formatDescriptor,
     ExternalUnit unitNumber, const char *sourceFile, int sourceLine) {
   return BeginExternalFormattedIO<Direction::Output>(format, formatLength,
       formatDescriptor, unitNumber, sourceFile, sourceLine);
 }
 
-Cookie IONAME(BeginExternalFormattedInput)(const char *format,
+Cookie IODEF(BeginExternalFormattedInput)(const char *format,
     std::size_t formatLength, const Descriptor *formatDescriptor,
     ExternalUnit unitNumber, const char *sourceFile, int sourceLine) {
   return BeginExternalFormattedIO<Direction::Input>(format, formatLength,
@@ -301,7 +300,7 @@ Cookie IONAME(BeginExternalFormattedInput)(const char *format,
 }
 
 template <Direction DIR>
-Cookie BeginUnformattedIO(
+RT_API_ATTRS Cookie BeginUnformattedIO(
     ExternalUnit unitNumber, const char *sourceFile, int sourceLine) {
   Terminator terminator{sourceFile, sourceLine};
   Cookie errorCookie{nullptr};
@@ -352,19 +351,19 @@ Cookie BeginUnformattedIO(
   }
 }
 
-Cookie IONAME(BeginUnformattedOutput)(
+Cookie IODEF(BeginUnformattedOutput)(
     ExternalUnit unitNumber, const char *sourceFile, int sourceLine) {
   return BeginUnformattedIO<Direction::Output>(
       unitNumber, sourceFile, sourceLine);
 }
 
-Cookie IONAME(BeginUnformattedInput)(
+Cookie IODEF(BeginUnformattedInput)(
     ExternalUnit unitNumber, const char *sourceFile, int sourceLine) {
   return BeginUnformattedIO<Direction::Input>(
       unitNumber, sourceFile, sourceLine);
 }
 
-Cookie IONAME(BeginOpenUnit)( // OPEN(without NEWUNIT=)
+Cookie IODEF(BeginOpenUnit)( // OPEN(without NEWUNIT=)
     ExternalUnit unitNumber, const char *sourceFile, int sourceLine) {
   Terminator terminator{sourceFile, sourceLine};
   bool wasExtant{false};
@@ -384,7 +383,7 @@ Cookie IONAME(BeginOpenUnit)( // OPEN(without NEWUNIT=)
   }
 }
 
-Cookie IONAME(BeginOpenNewUnit)( // OPEN(NEWUNIT=j)
+Cookie IODEF(BeginOpenNewUnit)( // OPEN(NEWUNIT=j)
     const char *sourceFile, int sourceLine) {
   Terminator terminator{sourceFile, sourceLine};
   ExternalFileUnit &unit{
@@ -394,7 +393,7 @@ Cookie IONAME(BeginOpenNewUnit)( // OPEN(NEWUNIT=j)
       sourceLine);
 }
 
-Cookie IONAME(BeginWait)(ExternalUnit unitNumber, AsynchronousId id,
+Cookie IODEF(BeginWait)(ExternalUnit unitNumber, AsynchronousId id,
     const char *sourceFile, int sourceLine) {
   Terminator terminator{sourceFile, sourceLine};
   if (ExternalFileUnit * unit{ExternalFileUnit::LookUp(unitNumber)}) {
@@ -410,12 +409,12 @@ Cookie IONAME(BeginWait)(ExternalUnit unitNumber, AsynchronousId id,
         terminator, unitNumber, id == 0 ? IostatOk : IostatBadWaitUnit);
   }
 }
-Cookie IONAME(BeginWaitAll)(
+Cookie IODEF(BeginWaitAll)(
     ExternalUnit unitNumber, const char *sourceFile, int sourceLine) {
   return IONAME(BeginWait)(unitNumber, 0 /*no ID=*/, sourceFile, sourceLine);
 }
 
-Cookie IONAME(BeginClose)(
+Cookie IODEF(BeginClose)(
     ExternalUnit unitNumber, const char *sourceFile, int sourceLine) {
   Terminator terminator{sourceFile, sourceLine};
   if (ExternalFileUnit * unit{ExternalFileUnit::LookUp(unitNumber)}) {
@@ -434,7 +433,7 @@ Cookie IONAME(BeginClose)(
   }
 }
 
-Cookie IONAME(BeginFlush)(
+Cookie IODEF(BeginFlush)(
     ExternalUnit unitNumber, const char *sourceFile, int sourceLine) {
   Terminator terminator{sourceFile, sourceLine};
   if (ExternalFileUnit * unit{ExternalFileUnit::LookUp(unitNumber)}) {
@@ -452,7 +451,7 @@ Cookie IONAME(BeginFlush)(
   }
 }
 
-Cookie IONAME(BeginBackspace)(
+Cookie IODEF(BeginBackspace)(
     ExternalUnit unitNumber, const char *sourceFile, int sourceLine) {
   Terminator terminator{sourceFile, sourceLine};
   if (ExternalFileUnit * unit{ExternalFileUnit::LookUp(unitNumber)}) {
@@ -470,7 +469,7 @@ Cookie IONAME(BeginBackspace)(
   }
 }
 
-Cookie IONAME(BeginEndfile)(
+Cookie IODEF(BeginEndfile)(
     ExternalUnit unitNumber, const char *sourceFile, int sourceLine) {
   Terminator terminator{sourceFile, sourceLine};
   Cookie errorCookie{nullptr};
@@ -490,7 +489,7 @@ Cookie IONAME(BeginEndfile)(
   }
 }
 
-Cookie IONAME(BeginRewind)(
+Cookie IODEF(BeginRewind)(
     ExternalUnit unitNumber, const char *sourceFile, int sourceLine) {
   Terminator terminator{sourceFile, sourceLine};
   Cookie errorCookie{nullptr};
@@ -510,7 +509,7 @@ Cookie IONAME(BeginRewind)(
   }
 }
 
-Cookie IONAME(BeginInquireUnit)(
+Cookie IODEF(BeginInquireUnit)(
     ExternalUnit unitNumber, const char *sourceFile, int sourceLine) {
   Terminator terminator{sourceFile, sourceLine};
   if (ExternalFileUnit * unit{ExternalFileUnit::LookUp(unitNumber)}) {
@@ -530,14 +529,14 @@ Cookie IONAME(BeginInquireUnit)(
   }
 }
 
-Cookie IONAME(BeginInquireFile)(const char *path, std::size_t pathLength,
+Cookie IODEF(BeginInquireFile)(const char *path, std::size_t pathLength,
     const char *sourceFile, int sourceLine) {
   Terminator terminator{sourceFile, sourceLine};
   auto trimmed{SaveDefaultCharacter(
       path, TrimTrailingSpaces(path, pathLength), terminator)};
   if (ExternalFileUnit *
       unit{ExternalFileUnit::LookUp(
-          trimmed.get(), std::strlen(trimmed.get()))}) {
+          trimmed.get(), Fortran::runtime::strlen(trimmed.get()))}) {
     // INQUIRE(FILE=) to a connected unit
     if (ChildIo * child{unit->GetChildIo()}) {
       return &child->BeginIoStatement<InquireUnitState>(
@@ -554,7 +553,7 @@ Cookie IONAME(BeginInquireFile)(const char *path, std::size_t pathLength,
   }
 }
 
-Cookie IONAME(BeginInquireIoLength)(const char *sourceFile, int sourceLine) {
+Cookie IODEF(BeginInquireIoLength)(const char *sourceFile, int sourceLine) {
   Terminator oom{sourceFile, sourceLine};
   return &New<InquireIOLengthState>{oom}(sourceFile, sourceLine)
               .release()
@@ -563,7 +562,7 @@ Cookie IONAME(BeginInquireIoLength)(const char *sourceFile, int sourceLine) {
 
 // Control list items
 
-void IONAME(EnableHandlers)(Cookie cookie, bool hasIoStat, bool hasErr,
+void IODEF(EnableHandlers)(Cookie cookie, bool hasIoStat, bool hasErr,
     bool hasEnd, bool hasEor, bool hasIoMsg) {
   IoErrorHandler &handler{cookie->GetIoErrorHandler()};
   if (hasIoStat) {
@@ -583,8 +582,8 @@ void IONAME(EnableHandlers)(Cookie cookie, bool hasIoStat, bool hasErr,
   }
 }
 
-static bool YesOrNo(const char *keyword, std::size_t length, const char *what,
-    IoErrorHandler &handler) {
+static RT_API_ATTRS bool YesOrNo(const char *keyword, std::size_t length,
+    const char *what, IoErrorHandler &handler) {
   static const char *keywords[]{"YES", "NO", nullptr};
   switch (IdentifyValue(keyword, length, keywords)) {
   case 0:
@@ -598,8 +597,7 @@ static bool YesOrNo(const char *keyword, std::size_t length, const char *what,
   }
 }
 
-bool IONAME(SetAdvance)(
-    Cookie cookie, const char *keyword, std::size_t length) {
+bool IODEF(SetAdvance)(Cookie cookie, const char *keyword, std::size_t length) {
   IoStatementState &io{*cookie};
   IoErrorHandler &handler{io.GetIoErrorHandler()};
   bool nonAdvancing{!YesOrNo(keyword, length, "ADVANCE", handler)};
@@ -616,7 +614,7 @@ bool IONAME(SetAdvance)(
   return !handler.InError();
 }
 
-bool IONAME(SetBlank)(Cookie cookie, const char *keyword, std::size_t length) {
+bool IODEF(SetBlank)(Cookie cookie, const char *keyword, std::size_t length) {
   IoStatementState &io{*cookie};
   static const char *keywords[]{"NULL", "ZERO", nullptr};
   switch (IdentifyValue(keyword, length, keywords)) {
@@ -633,8 +631,7 @@ bool IONAME(SetBlank)(Cookie cookie, const char *keyword, std::size_t length) {
   }
 }
 
-bool IONAME(SetDecimal)(
-    Cookie cookie, const char *keyword, std::size_t length) {
+bool IODEF(SetDecimal)(Cookie cookie, const char *keyword, std::size_t length) {
   IoStatementState &io{*cookie};
   static const char *keywords[]{"COMMA", "POINT", nullptr};
   switch (IdentifyValue(keyword, length, keywords)) {
@@ -651,7 +648,7 @@ bool IONAME(SetDecimal)(
   }
 }
 
-bool IONAME(SetDelim)(Cookie cookie, const char *keyword, std::size_t length) {
+bool IODEF(SetDelim)(Cookie cookie, const char *keyword, std::size_t length) {
   IoStatementState &io{*cookie};
   static const char *keywords[]{"APOSTROPHE", "QUOTE", "NONE", nullptr};
   switch (IdentifyValue(keyword, length, keywords)) {
@@ -671,14 +668,14 @@ bool IONAME(SetDelim)(Cookie cookie, const char *keyword, std::size_t length) {
   }
 }
 
-bool IONAME(SetPad)(Cookie cookie, const char *keyword, std::size_t length) {
+bool IODEF(SetPad)(Cookie cookie, const char *keyword, std::size_t length) {
   IoStatementState &io{*cookie};
   IoErrorHandler &handler{io.GetIoErrorHandler()};
   io.mutableModes().pad = YesOrNo(keyword, length, "PAD", handler);
   return !handler.InError();
 }
 
-bool IONAME(SetPos)(Cookie cookie, std::int64_t pos) {
+bool IODEF(SetPos)(Cookie cookie, std::int64_t pos) {
   IoStatementState &io{*cookie};
   IoErrorHandler &handler{io.GetIoErrorHandler()};
   if (auto *unit{io.GetExternalFileUnit()}) {
@@ -689,7 +686,7 @@ bool IONAME(SetPos)(Cookie cookie, std::int64_t pos) {
   return false;
 }
 
-bool IONAME(SetRec)(Cookie cookie, std::int64_t rec) {
+bool IODEF(SetRec)(Cookie cookie, std::int64_t rec) {
   IoStatementState &io{*cookie};
   IoErrorHandler &handler{io.GetIoErrorHandler()};
   if (auto *unit{io.GetExternalFileUnit()}) {
@@ -705,7 +702,7 @@ bool IONAME(SetRec)(Cookie cookie, std::int64_t rec) {
   return true;
 }
 
-bool IONAME(SetRound)(Cookie cookie, const char *keyword, std::size_t length) {
+bool IODEF(SetRound)(Cookie cookie, const char *keyword, std::size_t length) {
   IoStatementState &io{*cookie};
   static const char *keywords[]{"UP", "DOWN", "ZERO", "NEAREST", "COMPATIBLE",
       "PROCESSOR_DEFINED", nullptr};
@@ -735,7 +732,7 @@ bool IONAME(SetRound)(Cookie cookie, const char *keyword, std::size_t length) {
   }
 }
 
-bool IONAME(SetSign)(Cookie cookie, const char *keyword, std::size_t length) {
+bool IODEF(SetSign)(Cookie cookie, const char *keyword, std::size_t length) {
   IoStatementState &io{*cookie};
   static const char *keywords[]{
       "PLUS", "SUPPRESS", "PROCESSOR_DEFINED", nullptr};
@@ -754,7 +751,7 @@ bool IONAME(SetSign)(Cookie cookie, const char *keyword, std::size_t length) {
   }
 }
 
-bool IONAME(SetAccess)(Cookie cookie, const char *keyword, std::size_t length) {
+bool IODEF(SetAccess)(Cookie cookie, const char *keyword, std::size_t length) {
   IoStatementState &io{*cookie};
   auto *open{io.get_if<OpenStatementState>()};
   if (!open) {
@@ -790,7 +787,7 @@ bool IONAME(SetAccess)(Cookie cookie, const char *keyword, std::size_t length) {
   return true;
 }
 
-bool IONAME(SetAction)(Cookie cookie, const char *keyword, std::size_t length) {
+bool IODEF(SetAction)(Cookie cookie, const char *keyword, std::size_t length) {
   IoStatementState &io{*cookie};
   auto *open{io.get_if<OpenStatementState>()};
   if (!open) {
@@ -832,7 +829,7 @@ bool IONAME(SetAction)(Cookie cookie, const char *keyword, std::size_t length) {
   return true;
 }
 
-bool IONAME(SetAsynchronous)(
+bool IODEF(SetAsynchronous)(
     Cookie cookie, const char *keyword, std::size_t length) {
   IoStatementState &io{*cookie};
   IoErrorHandler &handler{io.GetIoErrorHandler()};
@@ -859,7 +856,7 @@ bool IONAME(SetAsynchronous)(
   return !handler.InError();
 }
 
-bool IONAME(SetCarriagecontrol)(
+bool IODEF(SetCarriagecontrol)(
     Cookie cookie, const char *keyword, std::size_t length) {
   IoStatementState &io{*cookie};
   auto *open{io.get_if<OpenStatementState>()};
@@ -891,8 +888,7 @@ bool IONAME(SetCarriagecontrol)(
   }
 }
 
-bool IONAME(SetConvert)(
-    Cookie cookie, const char *keyword, std::size_t length) {
+bool IODEF(SetConvert)(Cookie cookie, const char *keyword, std::size_t length) {
   IoStatementState &io{*cookie};
   auto *open{io.get_if<OpenStatementState>()};
   if (!open) {
@@ -916,7 +912,7 @@ bool IONAME(SetConvert)(
   }
 }
 
-bool IONAME(SetEncoding)(
+bool IODEF(SetEncoding)(
     Cookie cookie, const char *keyword, std::size_t length) {
   IoStatementState &io{*cookie};
   auto *open{io.get_if<OpenStatementState>()};
@@ -948,7 +944,7 @@ bool IONAME(SetEncoding)(
   return true;
 }
 
-bool IONAME(SetForm)(Cookie cookie, const char *keyword, std::size_t length) {
+bool IODEF(SetForm)(Cookie cookie, const char *keyword, std::size_t length) {
   IoStatementState &io{*cookie};
   auto *open{io.get_if<OpenStatementState>()};
   if (!open) {
@@ -976,7 +972,7 @@ bool IONAME(SetForm)(Cookie cookie, const char *keyword, std::size_t length) {
   return true;
 }
 
-bool IONAME(SetPosition)(
+bool IODEF(SetPosition)(
     Cookie cookie, const char *keyword, std::size_t length) {
   IoStatementState &io{*cookie};
   auto *open{io.get_if<OpenStatementState>()};
@@ -1009,7 +1005,7 @@ bool IONAME(SetPosition)(
   return true;
 }
 
-bool IONAME(SetRecl)(Cookie cookie, std::size_t n) {
+bool IODEF(SetRecl)(Cookie cookie, std::size_t n) {
   IoStatementState &io{*cookie};
   auto *open{io.get_if<OpenStatementState>()};
   if (!open) {
@@ -1036,7 +1032,7 @@ bool IONAME(SetRecl)(Cookie cookie, std::size_t n) {
   }
 }
 
-bool IONAME(SetStatus)(Cookie cookie, const char *keyword, std::size_t length) {
+bool IODEF(SetStatus)(Cookie cookie, const char *keyword, std::size_t length) {
   IoStatementState &io{*cookie};
   if (auto *open{io.get_if<OpenStatementState>()}) {
     if (open->completedOperation()) {
@@ -1090,7 +1086,7 @@ bool IONAME(SetStatus)(Cookie cookie, const char *keyword, std::size_t length) {
       "SetStatus() called when not in an OPEN or CLOSE statement");
 }
 
-bool IONAME(SetFile)(Cookie cookie, const char *path, std::size_t chars) {
+bool IODEF(SetFile)(Cookie cookie, const char *path, std::size_t chars) {
   IoStatementState &io{*cookie};
   if (auto *open{io.get_if<OpenStatementState>()}) {
     if (open->completedOperation()) {
@@ -1107,7 +1103,7 @@ bool IONAME(SetFile)(Cookie cookie, const char *path, std::size_t chars) {
   return false;
 }
 
-bool IONAME(GetNewUnit)(Cookie cookie, int &unit, int kind) {
+bool IODEF(GetNewUnit)(Cookie cookie, int &unit, int kind) {
   IoStatementState &io{*cookie};
   auto *open{io.get_if<OpenStatementState>()};
   if (!open) {
@@ -1135,15 +1131,15 @@ bool IONAME(GetNewUnit)(Cookie cookie, int &unit, int kind) {
 
 // Data transfers
 
-bool IONAME(OutputDescriptor)(Cookie cookie, const Descriptor &descriptor) {
+bool IODEF(OutputDescriptor)(Cookie cookie, const Descriptor &descriptor) {
   return descr::DescriptorIO<Direction::Output>(*cookie, descriptor);
 }
 
-bool IONAME(InputDescriptor)(Cookie cookie, const Descriptor &descriptor) {
+bool IODEF(InputDescriptor)(Cookie cookie, const Descriptor &descriptor) {
   return descr::DescriptorIO<Direction::Input>(*cookie, descriptor);
 }
 
-bool IONAME(OutputInteger8)(Cookie cookie, std::int8_t n) {
+bool IODEF(OutputInteger8)(Cookie cookie, std::int8_t n) {
   if (!cookie->CheckFormattedStmtType<Direction::Output>("OutputInteger8")) {
     return false;
   }
@@ -1154,7 +1150,7 @@ bool IONAME(OutputInteger8)(Cookie cookie, std::int8_t n) {
   return descr::DescriptorIO<Direction::Output>(*cookie, descriptor);
 }
 
-bool IONAME(OutputInteger16)(Cookie cookie, std::int16_t n) {
+bool IODEF(OutputInteger16)(Cookie cookie, std::int16_t n) {
   if (!cookie->CheckFormattedStmtType<Direction::Output>("OutputInteger16")) {
     return false;
   }
@@ -1165,7 +1161,6 @@ bool IONAME(OutputInteger16)(Cookie cookie, std::int16_t n) {
   return descr::DescriptorIO<Direction::Output>(*cookie, descriptor);
 }
 
-RT_EXT_API_GROUP_BEGIN
 bool IODEF(OutputInteger32)(Cookie cookie, std::int32_t n) {
   if (!cookie->CheckFormattedStmtType<Direction::Output>("OutputInteger32")) {
     return false;
@@ -1176,9 +1171,8 @@ bool IODEF(OutputInteger32)(Cookie cookie, std::int32_t n) {
       TypeCategory::Integer, 4, reinterpret_cast<void *>(&n), 0);
   return descr::DescriptorIO<Direction::Output>(*cookie, descriptor);
 }
-RT_EXT_API_GROUP_END
 
-bool IONAME(OutputInteger64)(Cookie cookie, std::int64_t n) {
+bool IODEF(OutputInteger64)(Cookie cookie, std::int64_t n) {
   if (!cookie->CheckFormattedStmtType<Direction::Output>("OutputInteger64")) {
     return false;
   }
@@ -1190,7 +1184,7 @@ bool IONAME(OutputInteger64)(Cookie cookie, std::int64_t n) {
 }
 
 #ifdef __SIZEOF_INT128__
-bool IONAME(OutputInteger128)(Cookie cookie, common::int128_t n) {
+bool IODEF(OutputInteger128)(Cookie cookie, common::int128_t n) {
   if (!cookie->CheckFormattedStmtType<Direction::Output>("OutputInteger128")) {
     return false;
   }
@@ -1202,7 +1196,7 @@ bool IONAME(OutputInteger128)(Cookie cookie, common::int128_t n) {
 }
 #endif
 
-bool IONAME(InputInteger)(Cookie cookie, std::int64_t &n, int kind) {
+bool IODEF(InputInteger)(Cookie cookie, std::int64_t &n, int kind) {
   if (!cookie->CheckFormattedStmtType<Direction::Input>("InputInteger")) {
     return false;
   }
@@ -1213,7 +1207,7 @@ bool IONAME(InputInteger)(Cookie cookie, std::int64_t &n, int kind) {
   return descr::DescriptorIO<Direction::Input>(*cookie, descriptor);
 }
 
-bool IONAME(OutputReal32)(Cookie cookie, float x) {
+bool IODEF(OutputReal32)(Cookie cookie, float x) {
   if (!cookie->CheckFormattedStmtType<Direction::Output>("OutputReal32")) {
     return false;
   }
@@ -1223,7 +1217,7 @@ bool IONAME(OutputReal32)(Cookie cookie, float x) {
   return descr::DescriptorIO<Direction::Output>(*cookie, descriptor);
 }
 
-bool IONAME(OutputReal64)(Cookie cookie, double x) {
+bool IODEF(OutputReal64)(Cookie cookie, double x) {
   if (!cookie->CheckFormattedStmtType<Direction::Output>("OutputReal64")) {
     return false;
   }
@@ -1233,7 +1227,7 @@ bool IONAME(OutputReal64)(Cookie cookie, double x) {
   return descr::DescriptorIO<Direction::Output>(*cookie, descriptor);
 }
 
-bool IONAME(InputReal32)(Cookie cookie, float &x) {
+bool IODEF(InputReal32)(Cookie cookie, float &x) {
   if (!cookie->CheckFormattedStmtType<Direction::Input>("InputReal32")) {
     return false;
   }
@@ -1243,7 +1237,7 @@ bool IONAME(InputReal32)(Cookie cookie, float &x) {
   return descr::DescriptorIO<Direction::Input>(*cookie, descriptor);
 }
 
-bool IONAME(InputReal64)(Cookie cookie, double &x) {
+bool IODEF(InputReal64)(Cookie cookie, double &x) {
   if (!cookie->CheckFormattedStmtType<Direction::Input>("InputReal64")) {
     return false;
   }
@@ -1253,7 +1247,7 @@ bool IONAME(InputReal64)(Cookie cookie, double &x) {
   return descr::DescriptorIO<Direction::Input>(*cookie, descriptor);
 }
 
-bool IONAME(OutputComplex32)(Cookie cookie, float r, float i) {
+bool IODEF(OutputComplex32)(Cookie cookie, float r, float i) {
   if (!cookie->CheckFormattedStmtType<Direction::Output>("OutputComplex32")) {
     return false;
   }
@@ -1265,7 +1259,7 @@ bool IONAME(OutputComplex32)(Cookie cookie, float r, float i) {
   return descr::DescriptorIO<Direction::Output>(*cookie, descriptor);
 }
 
-bool IONAME(OutputComplex64)(Cookie cookie, double r, double i) {
+bool IODEF(OutputComplex64)(Cookie cookie, double r, double i) {
   if (!cookie->CheckFormattedStmtType<Direction::Output>("OutputComplex64")) {
     return false;
   }
@@ -1277,7 +1271,7 @@ bool IONAME(OutputComplex64)(Cookie cookie, double r, double i) {
   return descr::DescriptorIO<Direction::Output>(*cookie, descriptor);
 }
 
-bool IONAME(InputComplex32)(Cookie cookie, float z[2]) {
+bool IODEF(InputComplex32)(Cookie cookie, float z[2]) {
   if (!cookie->CheckFormattedStmtType<Direction::Input>("InputComplex32")) {
     return false;
   }
@@ -1288,7 +1282,7 @@ bool IONAME(InputComplex32)(Cookie cookie, float z[2]) {
   return descr::DescriptorIO<Direction::Input>(*cookie, descriptor);
 }
 
-bool IONAME(InputComplex64)(Cookie cookie, double z[2]) {
+bool IODEF(InputComplex64)(Cookie cookie, double z[2]) {
   if (!cookie->CheckFormattedStmtType<Direction::Input>("InputComplex64")) {
     return false;
   }
@@ -1299,7 +1293,7 @@ bool IONAME(InputComplex64)(Cookie cookie, double z[2]) {
   return descr::DescriptorIO<Direction::Input>(*cookie, descriptor);
 }
 
-bool IONAME(OutputCharacter)(
+bool IODEF(OutputCharacter)(
     Cookie cookie, const char *x, std::size_t length, int kind) {
   if (!cookie->CheckFormattedStmtType<Direction::Output>("OutputCharacter")) {
     return false;
@@ -1311,11 +1305,11 @@ bool IONAME(OutputCharacter)(
   return descr::DescriptorIO<Direction::Output>(*cookie, descriptor);
 }
 
-bool IONAME(OutputAscii)(Cookie cookie, const char *x, std::size_t length) {
+bool IODEF(OutputAscii)(Cookie cookie, const char *x, std::size_t length) {
   return IONAME(OutputCharacter(cookie, x, length, 1));
 }
 
-bool IONAME(InputCharacter)(
+bool IODEF(InputCharacter)(
     Cookie cookie, char *x, std::size_t length, int kind) {
   if (!cookie->CheckFormattedStmtType<Direction::Input>("InputCharacter")) {
     return false;
@@ -1326,11 +1320,11 @@ bool IONAME(InputCharacter)(
   return descr::DescriptorIO<Direction::Input>(*cookie, descriptor);
 }
 
-bool IONAME(InputAscii)(Cookie cookie, char *x, std::size_t length) {
+bool IODEF(InputAscii)(Cookie cookie, char *x, std::size_t length) {
   return IONAME(InputCharacter)(cookie, x, length, 1);
 }
 
-bool IONAME(OutputLogical)(Cookie cookie, bool truth) {
+bool IODEF(OutputLogical)(Cookie cookie, bool truth) {
   if (!cookie->CheckFormattedStmtType<Direction::Output>("OutputLogical")) {
     return false;
   }
@@ -1341,7 +1335,7 @@ bool IONAME(OutputLogical)(Cookie cookie, bool truth) {
   return descr::DescriptorIO<Direction::Output>(*cookie, descriptor);
 }
 
-bool IONAME(InputLogical)(Cookie cookie, bool &truth) {
+bool IODEF(InputLogical)(Cookie cookie, bool &truth) {
   if (!cookie->CheckFormattedStmtType<Direction::Input>("InputLogical")) {
     return false;
   }
@@ -1352,17 +1346,17 @@ bool IONAME(InputLogical)(Cookie cookie, bool &truth) {
   return descr::DescriptorIO<Direction::Input>(*cookie, descriptor);
 }
 
-bool IONAME(OutputDerivedType)(Cookie cookie, const Descriptor &descriptor,
+bool IODEF(OutputDerivedType)(Cookie cookie, const Descriptor &descriptor,
     const NonTbpDefinedIoTable *table) {
   return descr::DescriptorIO<Direction::Output>(*cookie, descriptor, table);
 }
 
-bool IONAME(InputDerivedType)(Cookie cookie, const Descriptor &descriptor,
+bool IODEF(InputDerivedType)(Cookie cookie, const Descriptor &descriptor,
     const NonTbpDefinedIoTable *table) {
   return descr::DescriptorIO<Direction::Input>(*cookie, descriptor, table);
 }
 
-std::size_t IONAME(GetSize)(Cookie cookie) {
+std::size_t IODEF(GetSize)(Cookie cookie) {
   IoStatementState &io{*cookie};
   IoErrorHandler &handler{io.GetIoErrorHandler()};
   if (!handler.InError()) {
@@ -1379,7 +1373,7 @@ std::size_t IONAME(GetSize)(Cookie cookie) {
   return 0;
 }
 
-std::size_t IONAME(GetIoLength)(Cookie cookie) {
+std::size_t IODEF(GetIoLength)(Cookie cookie) {
   IoStatementState &io{*cookie};
   IoErrorHandler &handler{io.GetIoErrorHandler()};
   if (!handler.InError()) {
@@ -1395,7 +1389,7 @@ std::size_t IONAME(GetIoLength)(Cookie cookie) {
   return 0;
 }
 
-void IONAME(GetIoMsg)(Cookie cookie, char *msg, std::size_t length) {
+void IODEF(GetIoMsg)(Cookie cookie, char *msg, std::size_t length) {
   IoStatementState &io{*cookie};
   IoErrorHandler &handler{io.GetIoErrorHandler()};
   if (!handler.InError()) {
@@ -1406,7 +1400,7 @@ void IONAME(GetIoMsg)(Cookie cookie, char *msg, std::size_t length) {
   }
 }
 
-AsynchronousId IONAME(GetAsynchronousId)(Cookie cookie) {
+AsynchronousId IODEF(GetAsynchronousId)(Cookie cookie) {
   IoStatementState &io{*cookie};
   IoErrorHandler &handler{io.GetIoErrorHandler()};
   if (auto *ext{io.get_if<ExternalIoStatementBase>()}) {
@@ -1419,24 +1413,24 @@ AsynchronousId IONAME(GetAsynchronousId)(Cookie cookie) {
   return 0;
 }
 
-bool IONAME(InquireCharacter)(Cookie cookie, InquiryKeywordHash inquiry,
+bool IODEF(InquireCharacter)(Cookie cookie, InquiryKeywordHash inquiry,
     char *result, std::size_t length) {
   IoStatementState &io{*cookie};
   return io.Inquire(inquiry, result, length);
 }
 
-bool IONAME(InquireLogical)(
+bool IODEF(InquireLogical)(
     Cookie cookie, InquiryKeywordHash inquiry, bool &result) {
   IoStatementState &io{*cookie};
   return io.Inquire(inquiry, result);
 }
 
-bool IONAME(InquirePendingId)(Cookie cookie, AsynchronousId id, bool &result) {
+bool IODEF(InquirePendingId)(Cookie cookie, AsynchronousId id, bool &result) {
   IoStatementState &io{*cookie};
   return io.Inquire(HashInquiryKeyword("PENDING"), id, result);
 }
 
-bool IONAME(InquireInteger64)(
+bool IODEF(InquireInteger64)(
     Cookie cookie, InquiryKeywordHash inquiry, std::int64_t &result, int kind) {
   IoStatementState &io{*cookie};
   std::int64_t n{0}; // safe "undefined" value
@@ -1452,17 +1446,15 @@ bool IONAME(InquireInteger64)(
   return false;
 }
 
-RT_EXT_API_GROUP_BEGIN
 enum Iostat IODEF(EndIoStatement)(Cookie cookie) {
   IoStatementState &io{*cookie};
   return static_cast<enum Iostat>(io.EndIoStatement());
 }
-RT_EXT_API_GROUP_END
 
 template <typename INT>
-static enum Iostat CheckUnitNumberInRangeImpl(INT unit, bool handleError,
-    char *ioMsg, std::size_t ioMsgLength, const char *sourceFile,
-    int sourceLine) {
+static RT_API_ATTRS enum Iostat CheckUnitNumberInRangeImpl(INT unit,
+    bool handleError, char *ioMsg, std::size_t ioMsgLength,
+    const char *sourceFile, int sourceLine) {
   static_assert(sizeof(INT) >= sizeof(ExternalUnit),
       "only intended to be used when the INT to ExternalUnit conversion is "
       "narrowing");
@@ -1494,15 +1486,15 @@ static enum Iostat CheckUnitNumberInRangeImpl(INT unit, bool handleError,
   return IostatOk;
 }
 
-enum Iostat IONAME(CheckUnitNumberInRange64)(std::int64_t unit,
-    bool handleError, char *ioMsg, std::size_t ioMsgLength,
-    const char *sourceFile, int sourceLine) {
+enum Iostat IODEF(CheckUnitNumberInRange64)(std::int64_t unit, bool handleError,
+    char *ioMsg, std::size_t ioMsgLength, const char *sourceFile,
+    int sourceLine) {
   return CheckUnitNumberInRangeImpl(
       unit, handleError, ioMsg, ioMsgLength, sourceFile, sourceLine);
 }
 
 #ifdef __SIZEOF_INT128__
-enum Iostat IONAME(CheckUnitNumberInRange128)(common::int128_t unit,
+enum Iostat IODEF(CheckUnitNumberInRange128)(common::int128_t unit,
     bool handleError, char *ioMsg, std::size_t ioMsgLength,
     const char *sourceFile, int sourceLine) {
   return CheckUnitNumberInRangeImpl(
@@ -1525,3 +1517,5 @@ void std::__libcpp_verbose_abort(char const *format, ...) {
   std::abort();
 }
 #endif
+
+RT_EXT_API_GROUP_END
diff --git a/flang/runtime/io-error.cpp b/flang/runtime/io-error.cpp
index b006b82f62249..7a90966f81047 100644
--- a/flang/runtime/io-error.cpp
+++ b/flang/runtime/io-error.cpp
@@ -109,8 +109,6 @@ void IoErrorHandler::SignalPendingError() {
   SignalError(error);
 }
 
-RT_OFFLOAD_API_GROUP_END
-
 void IoErrorHandler::SignalErrno() { SignalError(errno); }
 
 bool IoErrorHandler::GetIoMsg(char *buffer, std::size_t bufferLength) {
@@ -127,7 +125,10 @@ bool IoErrorHandler::GetIoMsg(char *buffer, std::size_t bufferLength) {
   // in LLVM v9.0.1 with inadequate modification for Fortran,
   // since rectified.
   bool ok{false};
-#if HAVE_STRERROR_R
+#if defined(RT_DEVICE_COMPILATION)
+  // strerror_r is not available on device.
+  msg = "errno description is not available on device";
+#elif HAVE_STRERROR_R
   // strerror_r is thread-safe.
 #if defined(__GLIBC__) && defined(_GNU_SOURCE)
   // glibc defines its own incompatible version of strerror_r
@@ -157,4 +158,6 @@ bool IoErrorHandler::GetIoMsg(char *buffer, std::size_t bufferLength) {
     return false;
   }
 }
+
+RT_OFFLOAD_API_GROUP_END
 } // namespace Fortran::runtime::io
diff --git a/flang/runtime/io-error.h b/flang/runtime/io-error.h
index 0fe11c9185c0a..426573e2faf00 100644
--- a/flang/runtime/io-error.h
+++ b/flang/runtime/io-error.h
@@ -61,7 +61,7 @@ class IoErrorHandler : public Terminator {
   RT_API_ATTRS void SignalPendingError();
 
   RT_API_ATTRS int GetIoStat() const { return ioStat_; }
-  bool GetIoMsg(char *, std::size_t);
+  RT_API_ATTRS bool GetIoMsg(char *, std::size_t);
 
 private:
   enum Flag : std::uint8_t {
diff --git a/flang/runtime/namelist.cpp b/flang/runtime/namelist.cpp
index b502d41a8d5c8..b9eed2101ecfc 100644
--- a/flang/runtime/namelist.cpp
+++ b/flang/runtime/namelist.cpp
@@ -17,16 +17,20 @@
 
 namespace Fortran::runtime::io {
 
+RT_VAR_GROUP_BEGIN
 // Max size of a group, symbol or component identifier that can appear in
 // NAMELIST input, plus a byte for NUL termination.
-static constexpr std::size_t nameBufferSize{201};
+static constexpr RT_CONST_VAR_ATTRS std::size_t nameBufferSize{201};
+RT_VAR_GROUP_END
 
-static inline char32_t GetComma(IoStatementState &io) {
+RT_OFFLOAD_API_GROUP_BEGIN
+
+static inline RT_API_ATTRS char32_t GetComma(IoStatementState &io) {
   return io.mutableModes().editingFlags & decimalComma ? char32_t{';'}
                                                        : char32_t{','};
 }
 
-bool IONAME(OutputNamelist)(Cookie cookie, const NamelistGroup &group) {
+bool IODEF(OutputNamelist)(Cookie cookie, const NamelistGroup &group) {
   IoStatementState &io{*cookie};
   io.CheckFormattedStmtType<Direction::Output>("OutputNamelist");
   io.mutableModes().inNamelist = true;
@@ -40,7 +44,8 @@ bool IONAME(OutputNamelist)(Cookie cookie, const NamelistGroup &group) {
     if ((connection.NeedAdvance(prefixLen) &&
             !(io.AdvanceRecord() && EmitAscii(io, " ", 1))) ||
         !EmitAscii(io, prefix, prefixLen) ||
-        (connection.NeedAdvance(std::strlen(str) + (suffix != ' ')) &&
+        (connection.NeedAdvance(
+             Fortran::runtime::strlen(str) + (suffix != ' ')) &&
             !(io.AdvanceRecord() && EmitAscii(io, " ", 1)))) {
       return false;
     }
@@ -84,20 +89,20 @@ bool IONAME(OutputNamelist)(Cookie cookie, const NamelistGroup &group) {
   return EmitUpperCase("/", 1, "", ' ');
 }
 
-static constexpr bool IsLegalIdStart(char32_t ch) {
+static constexpr RT_API_ATTRS bool IsLegalIdStart(char32_t ch) {
   return (ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z') || ch == '_' ||
       ch == '@';
 }
 
-static constexpr bool IsLegalIdChar(char32_t ch) {
+static constexpr RT_API_ATTRS bool IsLegalIdChar(char32_t ch) {
   return IsLegalIdStart(ch) || (ch >= '0' && ch <= '9');
 }
 
-static constexpr char NormalizeIdChar(char32_t ch) {
+static constexpr RT_API_ATTRS char NormalizeIdChar(char32_t ch) {
   return static_cast<char>(ch >= 'A' && ch <= 'Z' ? ch - 'A' + 'a' : ch);
 }
 
-static bool GetLowerCaseName(
+static RT_API_ATTRS bool GetLowerCaseName(
     IoStatementState &io, char buffer[], std::size_t maxLength) {
   std::size_t byteLength{0};
   if (auto ch{io.GetNextNonBlank(byteLength)}) {
@@ -119,7 +124,7 @@ static bool GetLowerCaseName(
   return false;
 }
 
-static Fortran::common::optional<SubscriptValue> GetSubscriptValue(
+static RT_API_ATTRS Fortran::common::optional<SubscriptValue> GetSubscriptValue(
     IoStatementState &io) {
   Fortran::common::optional<SubscriptValue> value;
   std::size_t byteCount{0};
@@ -152,8 +157,8 @@ static Fortran::common::optional<SubscriptValue> GetSubscriptValue(
   return value;
 }
 
-static bool HandleSubscripts(IoStatementState &io, Descriptor &desc,
-    const Descriptor &source, const char *name) {
+static RT_API_ATTRS bool HandleSubscripts(IoStatementState &io,
+    Descriptor &desc, const Descriptor &source, const char *name) {
   IoErrorHandler &handler{io.GetIoErrorHandler()};
   // Allow for blanks in subscripts; they're nonstandard, but not
   // ambiguous within the parentheses.
@@ -252,7 +257,7 @@ static bool HandleSubscripts(IoStatementState &io, Descriptor &desc,
   return false;
 }
 
-static void StorageSequenceExtension(
+static RT_API_ATTRS void StorageSequenceExtension(
     Descriptor &desc, const Descriptor &source) {
   // Support the near-universal extension of NAMELIST input into a
   // designatable storage sequence identified by its initial scalar array
@@ -274,7 +279,7 @@ static void StorageSequenceExtension(
   }
 }
 
-static bool HandleSubstring(
+static RT_API_ATTRS bool HandleSubstring(
     IoStatementState &io, Descriptor &desc, const char *name) {
   IoErrorHandler &handler{io.GetIoErrorHandler()};
   auto pair{desc.type().GetCategoryAndKind()};
@@ -335,7 +340,7 @@ static bool HandleSubstring(
   return false;
 }
 
-static bool HandleComponent(IoStatementState &io, Descriptor &desc,
+static RT_API_ATTRS bool HandleComponent(IoStatementState &io, Descriptor &desc,
     const Descriptor &source, const char *name) {
   IoErrorHandler &handler{io.GetIoErrorHandler()};
   char compName[nameBufferSize];
@@ -344,7 +349,8 @@ static bool HandleComponent(IoStatementState &io, Descriptor &desc,
     if (const typeInfo::DerivedType *
         type{addendum ? addendum->derivedType() : nullptr}) {
       if (const typeInfo::Component *
-          comp{type->FindDataComponent(compName, std::strlen(compName))}) {
+          comp{type->FindDataComponent(
+              compName, Fortran::runtime::strlen(compName))}) {
         bool createdDesc{false};
         if (comp->rank() > 0 && source.rank() > 0) {
           // If base and component are both arrays, the component name
@@ -408,7 +414,7 @@ static bool HandleComponent(IoStatementState &io, Descriptor &desc,
 
 // Advance to the terminal '/' of a namelist group or leading '&'/'$'
 // of the next.
-static void SkipNamelistGroup(IoStatementState &io) {
+static RT_API_ATTRS void SkipNamelistGroup(IoStatementState &io) {
   std::size_t byteCount{0};
   while (auto ch{io.GetNextNonBlank(byteCount)}) {
     io.HandleRelativePosition(byteCount);
@@ -431,7 +437,7 @@ static void SkipNamelistGroup(IoStatementState &io) {
   }
 }
 
-bool IONAME(InputNamelist)(Cookie cookie, const NamelistGroup &group) {
+bool IODEF(InputNamelist)(Cookie cookie, const NamelistGroup &group) {
   IoStatementState &io{*cookie};
   io.CheckFormattedStmtType<Direction::Input>("InputNamelist");
   io.mutableModes().inNamelist = true;
@@ -470,7 +476,7 @@ bool IONAME(InputNamelist)(Cookie cookie, const NamelistGroup &group) {
       handler.SignalError("NAMELIST input group has no name");
       return false;
     }
-    if (std::strcmp(group.groupName, name) == 0) {
+    if (Fortran::runtime::strcmp(group.groupName, name) == 0) {
       break; // found it
     }
     SkipNamelistGroup(io);
@@ -489,7 +495,7 @@ bool IONAME(InputNamelist)(Cookie cookie, const NamelistGroup &group) {
     }
     std::size_t itemIndex{0};
     for (; itemIndex < group.items; ++itemIndex) {
-      if (std::strcmp(name, group.item[itemIndex].name) == 0) {
+      if (Fortran::runtime::strcmp(name, group.item[itemIndex].name) == 0) {
         break;
       }
     }
@@ -590,8 +596,6 @@ bool IONAME(InputNamelist)(Cookie cookie, const NamelistGroup &group) {
   return true;
 }
 
-RT_OFFLOAD_API_GROUP_BEGIN
-
 bool IsNamelistNameOrSlash(IoStatementState &io) {
   if (auto *listInput{
           io.get_if<ListDirectedStatementState<Direction::Input>>()}) {